Currently in continuous forms printing, there are three common means of recovering from a detected defect in the printed material. For the first method, the printer is stopped and the defective material is manually removed. This method is undesirable due to the high costs of the recovery since the high speed printer is stopped, the printed paper web 112 has to be cut crosswise and the defective material removed. As illustrated in FIG. 2A, additional pages must be removed since the crosswise cuts 215 and 235 of the printed paper web 112 must be done at a document boundary where no pages of a document extend above and below the cut line. For the example in FIG. 2A, page 2 of document 4 was found to be defective by a print inspection system. Since a re-print of document 4 will likely be scheduled, all 4 pages of document 4 must be removed. The removal of page 4 of document 4 along cut line 235 results in the removal of single page document 5. In addition, if the printed paper web is cut at location 220, page 3 of document 3 is also is removed making document 3 defective. Hence, all of document 3 must be removed by cutting the printed paper web at location 215. Three documents are lost and must be re-printed. Depending on the arrangement of documents on the printed paper web 112, many more documents might have to be removed. Additional problems occur with future document processing operations such as but not limited to roll to roll printing, roll winding and unwinding and operations of inserter or wrapper input channels. In either case, when the break in the printed paper web is processed the document processing system has to be stopped and reloaded. Each stop and reload further reduces production throughput and risks damaging additional document pages. For the reasons mentioned above, this is an expensive and time consuming option.
For the second method, print inspection system allows the defective material to proceed to the winder or fan-folder. Printer systems use marking devices to indicate the zone on the printed paper web or fan folded paper stack where the defect exists. During downstream processes, these zones are removed en masse from the printed material in a manner similar to the first method. The problem with this method is that a considerable amount of material has to be sacrificed to remove a single defect. The third method involves the printer throwing away all or most of the print run and re-printing the job.
Hence a need exists for a print inspection system that can detect a defective page in a document and uniquely identify that page and accompanying pages in the document. The defective document is then flagged for removal by a document processing system without stoppage of the printer, roller or document processing system by removing only the defective document from the production run.